Merge pull request #54 from Cebtenzzre/fix-literal-append

Fix action=append for List[Literal[...]]

Author: martinjm97

tap/tap.py

@@ -191,7 +191,8 @@ def _add_argument(self, *name_or_flags, **kwargs) -> None:
                       and len(get_args(var_type)) > 0
                       and is_literal_type(get_args(var_type)[0])):
                     var_type, kwargs['choices'] = get_literals(get_args(var_type)[0], variable)
-                    kwargs['nargs'] = kwargs.get('nargs', '*')
+                    if kwargs.get('action') not in {'append', 'append_const'}:
+                        kwargs['nargs'] = kwargs.get('nargs', '*')
                 # Handle Tuple type (with type args) by extracting types of Tuple elements and enforcing them
                 elif get_origin(var_type) in (Tuple, tuple) and len(get_args(var_type)) > 0:
                     loop = False

tests/test_actions.py

@@ -1,5 +1,6 @@
 import sys
 from typing import List
+from typing_extensions import Literal
 import unittest
 from unittest import TestCase
 
@@ -99,6 +100,16 @@ def configure(self):
         args = AppendListIntTap().parse_args('--arg 3 --arg 4'.split())
         self.assertEqual(args.arg, [1, 2, 3, 4])
 
+    def test_actions_append_list_literal(self):
+        class AppendListLiteralTap(Tap):
+            arg: List[Literal['what', 'is', 'up', 'today']] = ['what', 'is']
+
+            def configure(self):
+                self.add_argument('--arg', action='append')
+
+        args = AppendListLiteralTap().parse_args('--arg up --arg today'.split())
+        self.assertEqual(args.arg, 'what is up today'.split())
+
     def test_actions_append_untyped(self):
         class AppendListStrTap(Tap):
             arg = ['what', 'is']